Startup Wants Simple, App-Savvy Switches

SAN JOSE, Calif. — Network infrastructure needs to get radically simpler and focus on delivering application-layer performance, said the chief technology officer of one of the sector's most watched and still-secretive startups.

Tom Edsall of Insieme Networks, a startup spun off from Cisco Systems last year, laid out his design principles at a keynote at Hot Interconnects here. However, he would not discuss the details of his company's still-unannounced designs.

Most datacenters could operate on a relatively flat two-tier mesh of generally smaller switches than those currently in use, running a smaller set of still-emerging protocols and APIs, he said. Such a multipath fat tree or clos topology would reduce "today's network chokepoints -- we have to borrow from the world of compute and use a scale-out not scale-up model."

Today switches and routers are measured by their bandwidth, throughput, and feature sets. Engineers need to rethink the designs, measuring them first and foremost on their performance on network applications, Edsall said. This new perspective may imply throwing out current ideas about supporting fairness and quality of service in network flows, but each app has different requirements, and systems need to serve them flexibly.

These systems will also need updated debugging techniques suited to their multipath topologies. "We need at least a multipath-aware trace route and a ping that looks at all available instances" -- two of today's most popular debug techniques.

Edsall's keynote was followed closely by about 200 attendees at the Hot Interconnects event hosted at the Cisco campus here. The serial entrepreneur was a founder of Crescendo Communications, an Ethernet switching company that Cisco acquired, and Andiamo Systems, a storage networking group that Cisco incubated. His latest startup, Insieme, is seen as a big part of Cisco's answer to the potential disruptions posed by software-defined networking and the OpenFlow protocol born of work at Stanford.

Before Inseime's founding, he spent time as a visiting lecturer at Stanford. "The questions posed by the Open Networking Foundation have rocked the industry, but it takes a long time to introduce new technologies," he said.

Insieme representatives said in June that their systems would include both ASICs and merchant chips delivering security and network services to applications. They also said the systems would use new 100Gbit/s optical transceivers that use 10G cables.

It seems like they are trying to move enterprise networks from being general-purpose superhighways to being application-specific feeder roads. This may make sense in some specific applications, but it seems like there is a danger to making them too specific to particular applications which will change over time. SDNs are supposed to do that, but by allocating network resources at a software level which can adapt and change over time.

The argument for this is that enterprise applications don't change often. Unfortunately, baking the details into your network design is one way of ensuring that that description becomes even more self-fulfilling.

I'm not sure I understand what these "app-savvy switches" are really being asked to do, but I've always stayed away from any of these "fat tree" topologies, in my work.

Almost always, when I hear keynotes like this one, I know that I'm missing some key concept that the speaker has in mind. This would be no exception. Whether this key concept is generically applicable to networks, or whether it only applies to data centers, therefore escapes me.

My inclination has always been to design networks with many small switches, well distributed, in as dense a mesh as one can afford. This offers short paths between any two hosts and no prossibility of one or two switch failures creating a major catastrophy.

Interestingly both Edsall and a Googler who keynoted the day before (see link below) said protocols are still in an early definiton stage and OpenFlow is more of a starting point than a key piece of the SDN implementation.